How do I loosen the pinion cup nut?

[Tfrank59]

The splines are shot so I’ve got to change it, and I know it’s going to involve impact, but how do you hold the thing from turning in order to loosen that nut which I know has mucho torque on it?  Please help.

[Chrisj CMA]

With the final drive removed insert the flange and lay a stout piece of wood across engaging the pins. I just hold the board with a foot and use my cordless impact driver. Easy peasy

[Tfrank59]

Thanks Jeff.  Can’t believe how crappy my splines look after this interval. Did something wrong on lubing last time

[0leman]

When I replaced my pinon cup several years ago, I was able to hold the cup with a belt wrench and impact driver.  Work great.

[Bagger John - #3785]

There's a Honda tool to hold it. I have one in my rollaway though without looking at the service manual, I forget the Honda P/N.

As others pointed out, use whatever works plus an impact driver.

[Tfrank59]

I’m pretty sure what happened is the grease seal failed the one you know that keeps grease in the pinion cup. That sucks cause I had that red rust stuff so my Pinion cup and driveshaft splines are toast.  I bet it wouldn’t even last 5000 miles before I’d be stuck on the side of the road 

[98valk]

I’m pretty sure what happened is the grease seal failed the one you know that keeps grease in the pinion cup. That sucks cause I had that red rust stuff so my Pinion cup and driveshaft splines are toast.  I bet it wouldn’t even last 5000 miles before I’d be stuck on the side of the road 

here is my report of my recent failure

So my conclusion is to make sure the U-Joint splines are correctly lubricated, to prevent the drive shaft to final drive splines aka spline coupling (SC) from wearing out.

The SC in a perfect application would have zero forward/rearward movement and would be submerged in oil which would result in zero wear and fretting. Fretting is a type of corrosion which gives that rust powder look. Is not from water intrusion. In some applications they actually glue the splines together to stop movement.

Honda provided the locking spring clip on the SC end of the drive shaft to help reduce movement of the SC, but it is still not a solid zero movement connection. So this is where the lubricated U-joint splines come into effect, thereby doing all of the movement, to reduce or actually eliminate any SC movement.

In a few of the links I provide it is stated that the SC splines should be hardened to greatly reduce wear.  Did Honda do this to the parts?, it doesn't seem like they did, since that would have been a much higher cost.

In my case I inadvertently mixed greases with different bases for the u-joint splines, by re-greasing and not cleaning off the old grease.
My fault, at the time, I didn't realize they had different bases. So what happened the greases started to dry out and not provide the easy sliding movement as needed and the SC failed in 17k miles.

For re-installing the U-Joint boot I coated the inside lips with silicone grease and it pops on with zero problems. suggest not to use a silicone spray which has petroleum products in it and other things which could degrade the boot material.

So to bring this all together, proper lubrication of the u-joint splines is extremely important and should be done every tire change to protect the SC. 
This time I used moly bearing chassis grease for the U-Joint for even more friction reduction and easier sliding.

For the SC I mixed TS-70 moly paste with some high temp grease so there would be about a 50/50 moly to grease ratio as recommended by the Dan Foss pdf which is a much higher percent of moly than the 3% moly grease the Honda manual calls for.

The following documents have some very good info about SCs and lubrication requirements.

https://www.machinerylubrication.com/Read/693/fretting-wear

https://www.powertransmission.com/issues/0214/spline-couplings.pdf

https://assets.danfoss.com/documents/76142/AI152986482538en-000304.pdf

https://www.eng-tips.com/viewthread.cfm?qid=423609

https://gearsolutions.com/departments/tooth-tips-a-brief-overview-of-splines/

https://www.eng-tips.com/viewthread.cfm?qid=383504

http://www.valkyrieforum.com/bbs/index.php/topic,116696.40.html

[Tfrank59]

That’s all good information but if the seal in your pinion cup fails as mine did all the lubrication comes out it’s just a question of how soon and how much damage will happen before you realize there’s no seal holding the grease in. This is the dilemma with these final drives, because I have a 2002 Honda VTX 1800 with the same final drive although it’s on the left side of the bike, and I’m wondering should I pull the thing apart and take a look at it or wait until it needs a rear tire? It’s a lot of work to take it apart

[The emperor has no clothes]

That’s all good information but if the seal in your pinion cup fails as mine did all the lubrication comes out it’s just a question of how soon and how much damage will happen before you realize there’s no seal holding the grease in. This is the dilemma with these final drives, because I have a 2002 Honda VTX 1800 with the same final drive although it’s on the left side of the bike, and I’m wondering should I pull the thing apart and take a look at it or wait until it needs a rear tire? It’s a lot of work to take it apart

This is my thinking on this. It’s just that, my thinking on it. I have no engineering data to back it up, just my experience dealing with Valkyries. I think the purpose of the seal is not so much to keep the grease in, but to keep water out. Once my seal had worn and worked it’s way up the shaft and was not sealing in any way. The grease stayed in place. But we don’t get much rain here for any water to work its way in.

[Tfrank59]

I don’t think water is getting in to the pinion cup through the swing arm. I ride in a little bit of rain occasionally, but there’s never been any water inside my swing arm. I think the seal is to keep grease in. Just my opinion

[The emperor has no clothes]

I don’t think water is getting in to the pinion cup through the swing arm. I ride in a little bit of rain occasionally, but there’s never been any water inside my swing arm. I think the seal is to keep grease in. Just my opinion

You might be right.